Hydraulic tappet



1940- v c. E. JOHNSON ET AL 2,220,336

HYDRAULIC TAPPET Filed Jan. 22, 1940 \hverfl'o'rs Qhaflas I. doh songaudl Beagmann 4 w ow-9 Aiflbmegg Patented Nov. 5, 1940 UNITED STATESPATENT OFFICE.

HYDRAULIC IAPIPE'I tion of Michigan Application January 22, 1940, SerialNo. 314,934

3 Claims.

This invention relates to self-adjusting valve tappets used in internalcombustion engines, of the type which are automatically hydraulicallyoperated. The present invention is directed to useful improvements inhydraulic self-adjusting valve tappets to attain economy of productionand ease of assembly, and wherein the oil in an oil reservoir chamber islocated above the hydraulic or pressure sustaining chamber, said latterchamber being maintained with oil therein so that there will be no gapsbetween an end of the tappet and the end of a valve stem which restsagainst the tappet, the valve on said valve stem being moved in theusual manner by a rotating cam shaft against a relatively heavy valvespring to open a port in the engine.

With the construction which we have devised, the length of the tappetmay be materially reduced, thereby making it possible to use these valve.tappets in restricted spaces between a cam shaft and the end of thevalve stem of the valve with which it is associated. Furthermore, theassembly of the parts to make up the valve tappet is accomplishedwithout requiring any pressing fits which would be liable to distort thethin walls of the tappet body, and there is a further novel constructionwhich eliminates any danger of the parts binding against each other ortilting so as to permit escape of oil which would materially reduce ordefeat the efficiency of the tappet.

Various other objects and purposes with novel constructions for securingthe same will be apparent upon an understanding of the invention, hadfrom the following description taken in connection with the accompanyingdrawing, in which:

Fig. 1 is a vertical section taken centrally of a valve tappet in oneform embodying our invention, and

Fig. 2 is a horizontal section substantially on the plane of line 2-2 ofFig. 1, looking downwardly as indicated.

Like reference characters refer to like parts in the different figuresof the drawing.

In the construction of the tappet a hollow cylindrical body I of castmetal, preferably cast iron, is provided, being integrally closed at itslower end, as at 2. Around the outer curved side of the body a shallowand relatively wide continuous horizontal groove 3 is made, from whichat one point a vertical groove 4 extends upwardly to join with anopening 5 made through the wall l of the tappet body to the interiorspace thereof. The tappet body at such interior space is machined tocylindrical form and at the bottom of the opening a flat seat 6 isprovided on the upper side of the closed end 2, joining with thevertical cylindrical walls by a conical section as shown.

A coiled compression spring I is seated at its lower end upon said fiatseat 6 and is guided to a central position thereon by reason of theconical section previously mentioned. A ring 8 of T-shape in crosssection as shown, parted at one side at 9, is inserted within thecylindrical body I, the'inwardly extending leg of the T-shaped sectionbearing against the upper end of the spring 7. This ring 8 hassimilarities to piston ring packings, that is, the ring normally tendsto spring open at the parting for a short distance when free to do so,so that whenit is placed within a cylindrical opening and is contractedto substantially close the parting, its tendency to spring outwardlycauses the outer curved surface of the ring to bear with pressureagainst the cylindrical walls of the cylinder in which it is located.The ring 8 at one side, substantially oppositethe parting 9, carries abar ID of spring material, the purpose of which, as will later appear,is the'same as that-disclosed in the patent to C. E. Johnson, No.2,175,465, granted October 10, 1939.

A member is placed in the cylinder overthe ring 8 which includes anupper flange II, the exterior diameter of which is slightly less thanthe interior diameter of the body I, and from the flange a cylindricalsleeve l2 extends downwardly through the ring 8, with the spring bar inbearing against one side of the sleeve and flexed outwardly so that thetendency of the spring bar to return to its normal position pushes theflange ll against'the interior wall of the tappet body I over theparting 9 of the ring. Said sleeve 12 between its upper and lower endsis provided with an integral inwardly extending continuous annular ledgeIS with a central opening through it, and above which, is a downwardlyextending cylindrical opening M, at the lower end of which the ledge 13is machined to provide a substantially conical seat l5. At the lowerside of the ledge l3 and covering the central opening therethrough, avalve l6 of thin flat metal is located which is normally held in anupper position to close said opening, by a light strength coiled springH, the lower .coil of which is seated in a groove adjacent the lower endof the sleeve l2.

In the upper portion of the tappet a member is located including acentral stem l8, at the upper portion of which is an outwardly extendingcontinuous annular flange [9,- which like the flange II, has an exteriordiameter slightly less than the interior diameter of the tappet body;and above the flange and directly over the stem I8 is a head 20, againstthe outer end of which the end of a valve stem may bear, with the lowerend 2 of the tappet body bearing against a cam on a cam shaft. The stemI8 is of sleeve-like form, having a central vertical opening 2| therein,an opening 22 being made through the upper portion of the stem and asecond opening 23 near the lower portion thereof to communicate with theinterior 2|. The lower end of the stem is shaped so that it seatsagainst the conical seat I5 previously described. A parted snap springretaining ring 24 is seated in a groove adjacent the upper end of thetappet body and engages with the flange I9 to hold the assembly togetherwhen the tappet is not in an engine.

In the manufacture of the tappet the body may be completely machined andfinish-ed at its outer surfaces and also its inner cylindrical wall andthe seating face 6 completely machined and finished. Then the partswhich are assembled therewith are merely introduced one after the otherinto the tappet body, first the spring I, then .the split ring 8,thereafter the member having the flange II and sleeve I2 thereofinserted in place, valve I6 and spring ll having first been put inplace, passing freely into the tappet body without the necessity of anypress fits which would distort the relatively thin walls of the body,and thereafter the last member consisting of the stem I8, flange I9 andhead 20, with a snapping of the retaining ring 24 in place at the end ofthe assembly.

It is of course to be understood that the tappet in use is installed ina tappet guide sleeve therefor and that the oil under pressure from theoil system of the engine is pumped so that the space made by the groove3 between the tappet body and the surrounding guide sleeve iscontinuously filled with oil under pressure. This is old and well knownin the art and is shown for example in the Patent No. 2,145,484, issuedJanuary 31, 1939, to Charles E. Johnson. Said oil under pressure willfollow the groove at 4 to the opening 5, thence into the oil supplyreservoir chamber 25, which surrounds the vertical stem I8 and islocated between the flanges I0 and IS. The exterior diameter of the stemI8 is less than the interior diameter of the recess at I4 so that theoil can flow freely through the passage at 23 into the vertical openingin said stem IB and thence come against the upper side of the valve I 6.

In the operation of the engine, if the chamber at 26 below the flange IIis not sufliciently filled with oil, the pumping action which takesplace through the downward and upward movement of said flange II underthe pressure influ ence of the valve stem against the head 29, and areturn movement imparted by the spring 1, will cause the valve I6 tounseat on said return movement and permit oil .to flow into the chamber26 until it is sufliciently filled that further reciprocating movementof said flange II and the parts associated therewith does not takeplace. The chamber 26 which may be called a hydraulic or pressurechamber .is thus automatically filled with oil to the necessary amountand extent, immediately after the engine has been started, if at thetime the engine is started there is any deficiency of oil in the chamber26. The opening at 22 permits any escape of air which may arise from theoil within the stem I8.

In this construction it will be noted. that the bar II) which moves theflange I I to the left and over the parting 9 in the ring 8, does not,because of such movement, affect the vertical position of the stem I8 orthe horizontal position of the flange I9. Thus there is no binding ofsaid flange I9 against the inner cylinder walls of the tappet body, noris there any tilting of the flange to the horizontal or lateral movementthereof which would make a vertical separation at any point from theinner walls of the body I. This is a desirable feature of the invention,insuring against undue and excessive leakage of oil which might renderthe operation of the valve ineffective.

The location of the oil supply reservoir above the hydraulic chamber isa desirable feature of this invention. Within the hydraulic chamber 26oil free of air is maintained at all times in the proper amount so thatthe tappet and the end of the valve stem are not separated during engineoperation, resulting in noiseless operation of the tappets irrespectiveof the temperature conditions under which the tappets and Valvesoperated. Oil in the reservoir chamber 25 is in sufiicient amount at alltimes and is maintained in the chamber so as to be always available tofeed to the hydraulic chamber. Being heldinthe upper supply or reservoirchamber 25 for a considerable time, any air in the oil separates andrises therefrom, so that when oil passes to the chamber 26 it is free ofair. By having the hydraulic chamber at the lowest portion of the tappetbody and utilizing space above for the oil supply, the tappet may bematerially decreased in length. The machine operations and the assemblyare of the simplest and most economical type.

The invention is defined in the appended claims and is to be consideredcomprehensive of all forms of structure coming within their scope.

We claim:

1. A valve tappet comprising, a hollow tappet body closed at its lowerend, a member within the lower portion of said body having at its upperend an annular outwardly extending flange slightly less in diameter thanthe interior diameter of the body, and having a downwardly extendingsleeve portion with a vertical opening rtherethrough, the upper endportion of said opening being of larger diameter than a lower portionthereof, a split packing ring within the body below said flange engagingat its upper side against the lower outer edge portions thereof, acoiled compression spring between said ring and lower closed end of thebody, a second member located within the upper portion of the bodycomprising an annular flange of substantially the same diameter as theflange on the first member and a stem extending downwardly into theenlarged upper end portion of said opening in the first member, saidstem bearing at its lower end against said first member around the upperend of the reduced portion of the vertical openin-g thereth'rough, therebeing provided an oil receiving chamber between the flanges of saidfirst and second members, and a yielding spring member carried by saidring, pressing against a side of the sleeve of said first; member, saidspring member being located substantially opposite the parting in thering, said tappet body having a passage through the wall thereof leadingto said chamber between said flanges, as and for the purposes specified.

2. A valve tappet comprising, a hollow tappet body closed at its lowerend, a member within the lower portion of said body having at its upperend an annular outwardly extending flange slightly less in diameter thanthe interior diameter of the body and having a downwardly extendingsleeve portion with a vertical opening therethrough, the upper endportion of said opening being of a larger diameter than the lowerportion thereof, a second member within the body having an annularflange of substantially the same diameter as the first flange and havinga downwardly extending stem which enters the upper enlarged portion ofsaid opening in the first member and bears at its lower end against thefirst member, there being an oil receiving chamber between said flanges,said tappet body having an opening through a side thereof joining withsaid chamber, and said second member having a head at its upper endagainst which the end of a valve stem is adapted to engage, spring meansyieldingly holding said first member against the lower end of said stem,and means for controlling the passage of oil from said oil receivingchamber downwardly through said opening in the first member, asspecified.

3; A valve tappet comprising, a hollow tappet body closed at its lowerend, a member within the lower portion of said body having at its upperend an annular outwardly extending flange slightly less in diameter thanthe interior diameter of the body and having a downwardly extendingsleeve portion with a vertical opening therethrough, the upper endportion of said opening being of larger diameter than the lower portionthereof, a split packing ring within the body below said flange engagingat its upper side against the lower outer edge portions of the flange, acoiled spring between said ring and lower closed end of the body, avalve extending across and closing said passage, a light spring normallyelevating the valve into upper closing position, a second member havinga flange of substantially the same diameter as the flange on the firstmember and a central stem extending downwardly therefrom into the largerupper end portion of said opening in the firstmember, the lower end ofthe stem normally bearing at its lower end against said first member,said stem having a vertical opening therein from its lower end upwardlyfor a distance, and having a lateral opening connecting the interior ofthe stem with the chamber in the body between the flanges of said twomembers, and said body having an opening through a side thereof betweensaid flanges.

CHARLES E. JOHNSON;

PAUL F. BERGMANN.

